A hydropneumatic tank is a ground mounted pressure vessel which is used to store water for delivery under pressure to a water system without the necessity of using an elevated tank to develop the necessary system pressure. These tanks operate by using compressed air to force the stored water into the distribution line. As water exits the tank, the tank pressure drops, and after a preset quantity of water has exited the tank, more water is pumped into it.
It is necessary to control the level of water in a hydropneumatic tank. Usually, it is desired to maintain a minimum of 10 to 40 percent of the tank volume filled with water, but the actual amount depends upon the particular system with which the tank is connected and the use made of the water. Obviously, maintaining the water level is important because equipment receiving water from the system could be damaged if no water is received or if pressured air gets into the water system lines.
Control of such a system is compounded by the fact that usually the hydropneumatic tanks and controls are located in remote areas, preferably close to the water supply, and are not closely supervised. Such systems frequently also are located in unsheltered areas open to the rain and hot sunshine, thereby establishing a very difficult environment in which to operate. Additionally, certain malfunctions can occur which if not guarded against, can result in overpressurizing of the tank causing a very dangerous condition.
It is the purpose of this invention to provide an improved control and apparatus for maintaining the air-water volume in a hydropneumatic tank.